London School of Hygiene & Tropical Medicine

Receiving the largest ever research grant awarded specifically for yaws and the first to be funded by the European and Developing Countries Clinical Trials Partnership (EDCTP), the project aims to assess the real-life accuracy of a new diagnostic test in yaws-endemic areas of Ghana, Côte d’Ivoire and Cameroon.

Yaws is a chronic disfiguring and debilitating infectious disease caused by the Treponema pallidum bacteria. It predominantly affects children, resulting in chronic lesions in the skin, and severe destructive lesions in the bones and cartilage if left untreated.

According to the World Health Organization (WHO), there are 15 countries currently known to be endemic for yaws, which can be treated with a single oral dose of the antibiotic azithromycin.

The project will be undertaken in partnership with the Noguchi Memorial Institute for Medical Research (Ghana), the Institut Pasteur (Côte d’Ivoire), the Centre Pasteur (Cameroon), Fundació Lluita contra la Side i les Malaties Infeccioses (Spain), University of Göettingen, University of Freiburg and Mast Diagnostica (Germany).

Major barriers to yaws eradication programmes include delayed diagnosis and detection of drug resistance due to limited resources requiring samples being shipped to specialised labs for analysis. These delays contribute to ongoing transmission of the disease, and mean undiagnosed individuals do not receive effective treatment.

Earlier diagnosis and treatment of yaws can contribute to achieving the WHO’s ‘Sustainable Development Goal’ 3 – to ensure healthy lives and promote wellbeing for all at all ages.

Dr Michael Marks, Associate Professor of Infectious Diseases at LSHTM, is leading the team developing a new diagnostic test called loop-mediated isothermal amplification, or the LAMP test. It is a highly specific and sensitive point-of-care test, which analyses the DNA collected via swabs from the skin lesion without using expensive equipment, making it practical to use in resource-limited areas.

In the lab, the test can rapidly identify whether the individual has a T. pallidum infection, and can diagnose it with 95.7% accuracy. However, it’s effectiveness needs to tested in a real-life setting.

Dr Marks said:

“Yaws is a debilitating disease which affects society’s poorest, mainly children. There is an urgent need to drive the development of new diagnostic tests due to limitations of existing yaws tests, as well as the bacteria’s emerging resistance to treatment. The LAMP test could be the answer, we aim to find out.”

The researchers will look at the cost-effectiveness of the test and how easily it can be rolled out into local communities – two factors which will impact the uptake and success of the test.

Dr Marks explained: “Community engagement is central to all yaws eradication activities, so we will be interviewing patients to address patient, community and health-system concerns which could impact the implementation of the test.”

The research team will also support national programmes to strengthen their laboratory network, which will facilitate the roll-out of azithromycin mass drug administration to achieve the ultimate goal of yaws eradication.

Dr Emma Harding-Esch, co-investigator at LSHTM, said: “Accurate diagnostics are a key tool in supporting national programmes achieve high quality prevalence data, to aid data-driven decision making for yaws eradication.”